Page 189 - Handbook of Properties of Textile and Technical Fibres

166 Handbook of Properties of Textile and Technical Fibres

atomic to the macroscale, as in many biomaterials (Su and Buehler, 2016). At the
subnanometric scale, silk is a macromolecular polyamide chain. Polyalanine-rich
regions are expected to form b-ribbons that form b-sheet nanocrystals embedded in
“amorphous” glycine-rich phase and may form fibrils in which the amorphous chain
may have some preferential orientation along the fiber axe (Asakura et al., 2015a,b).
The fibrils are bundled together to finally form the fiber. Fig. 5.15 compares the differ-
ential scanning calorimetry (DSC) traces recorded for a semicrystalline polymer, the

(a) (4) Regenerated film (2) Gland
(3) Bombyx mori flotte (1) Polyamide 66
116 292

131 302 315 (4)

endo--> 73 (3)

258
<--exdo (2)

(1)

–50 0 50 100 150 200 250 300 350 400
Temperature / °C

(b) (4) Degummed Bombyx mori (2) Gonometa rufobrunea
(3) Raw Tussah silk (1) Samia cynthia (cocoon)
322
135
332
endo--> 122
(4)
(3)
127 231 346
<--exdo (2) 117 375
(1)

–50 0 50 100 150 200 250 300 350 400
Temperature / °C
Figure 5.15 Comparison of the differential scanning calorimetry traces: (a), (1) PA66 synthetic
fiber, (2) Bombyx mori silk precursor (dried gland central part), (3) washed silk fiber (flotte), and
(4) regenerated film; (b) (1) wild Samia cynthia riccini, (2) wild Gonometa rufobrunea, (3)
Tussah fiber, and (4) degummed B. mori.